Electrical connectors



April 28, 1964 J. s. ZDANIS ELECTRICAL CONNECTORS Filed April 25, 1962 INVENTOR JOHN S. ZDAN/S ATTORNEYS United States Patent 3,131,015 ELECTRICAL CONNECTORS John S. Zdanis, Watertown, C0nn., assignor to The Siemon Company Filed Apr. 25, 1962, Ser. No. 190,173 1 Claim. ((31. 339--97) This invention relates to electrical connectors.

Terminal connecting blocks are used extensively in the Wire communications industry to provide a convenient and orderly means of making mass wire terminations. For example, they are used by the telephone industry in distribution cabinets for connecting conductors in a cable from an exchange to other conductors extending to various stations within a building or to other limited areas of service. Such connecting blocks must be constructed to allow ready connection of new subscribers and the disconnection of subscribers Whose service is terminated. Therefore, solderless connections are generally used.

Solderless connections depend on pressure or stress exerted by the connecting apparatus on the conductors to insure intimate electrical contact and to hold the conductors in place. Many types of solder-less connections are known; such as, for example, sockets or plugs wherein a male element is inserted into a female element. One of the most common types of solderless connections used in terminal connecting blocks such as are used by the telephone industry is the screw connection. This may comprise a base of insulating material in which there are embedded a plurality of threaded terminals or posts, each post being provided with a nut. The terminals are generally arranged in two parallel rows. A connection of a conductor coming from the exchange with a conductor or conductors going to the individual subscribers may be made on a single post by Wrapping the conductors around the post and then tightening the nut. On the other hand, the terminals in one of the parallel rows may be connected to the incoming conductor from the exchange and the terminals in the other row may be connected to the conductors going to the subscribers. Connections between the two rows of terminals may be made, for example, by means of bridging wires. To use this type of terminal connecting block, it is necessary to strip the insulation from the ends of the conductors, wrap them around the post and then tighten the nut to insure good contact and to hold the conductors in place. This type of terminal connecting block is subject to several disadvantages. In addition to the fact that the insulation must be manually stripped from the end of the conductor before it is connected to a terminal, it has been found that the pressure of the nut pressing down on the stud which is resisted by the upward thrust of the stud, results in metal fatigue, especially in the threads of the stud; and, after a period of time, results in a poor contact with the connector. Moreover, only a limited number of connections can be made effectively at any one terminal post. Furthermore, when the connecting block is subjected to sustained periods of vibration, the nuts have a tendency to become loose and contact with the conductors may be lost.

It is an object of this invention to provide an electrical connector which automatically strips the insulation from the conductor and makes the required contact. It is another object of this invention to provide a terminal connector which will maintain good electrical contact indefinitely. It is a further object of this invention to provide a terminal connecting block which will permit a number of connections to be made on one terminal. Still another object of this invention is to provide an electrical connector that is capable of positively engaging a conductor for long periods of time, even under vibration, without deteriorating as a result of metal fatigue in the connector. Other objects will appear hereinafter.

3,131,015 Patented Apr. 28, 1964 Briefly, the objects of this invention are attained by providing a novel electrical connector which may be embedded in a base member of a suitable electrical insulating material. At least one, and preferably several upright or vertically disposed helical connectors may be embedded in the base member. The helical connectors are in the form of a continuous spiral of a suitable resilient conducting material which forms a plurality of closely spaced adjacent compact coils. The cross-sectional shape of the spiral strip comprising each coil is bounded on each surface thereof by angularly disposed planar surfaces rather than circular or arcuate surfaces.

The invention will be more particularly described with reference to the accompanying drawings wherein:

FIGURE 1 is a side elevational view of a helical connector constructed according to this invention.

FIGURE 2 is a partial cross-sectional view of a helical electrical conductor constructed according to this invention.

Referring more particularly to the drawings, there is shown a helical connector 20 formed by shaping a strip of resilient material into a continuously ascending spiral thereby providing a plurality of compact coils 21. The cross-sectional shape of the strip from which the coil is formed must be angular.

While the adjacent coils of the connector may be contiguousi.e., so compact that they are actually in contact or touching one an0therit is preferred that a small space separate the adjacent coils 21. The space should not be larger than the diameter of the conductor wire which is to be connected thereto.

The number of coils in each helical connector is not particularly critical and is largely a matter of choice. The actual number will be dictated by the number of connections which it is desired to make on each connector. Generally, the helical connectors of this invention will be comprised of at least four coils.

The connector may be constructed of any suitable resilient conducting material and is preferably a metal such as Phosphor-bronze, beryllium-copper, etc. It is preferred that the metal be plated with tin to prevent corrosion of the connector.

It is essential that the configuration of the cross-sectional shape of the strip from which the coils in the helical connectors of this invention are formed be bounded by surfaces that are angularly disposed to one another rather than circular. By angular cross-section, it is meant that the periphery of the cross-section meets in at least one well defined point to form an angle. Thus, the surface of the strip from which the coils are formed contains at least two longitudinal surfaces which meet at an abrupt converging sharp edge on the surface of the coils in the connector.

Helical connectors constructed according to this invention may be used in various environments. In a preferred embodiment, at least one helical connector is embedded in a suitable base member to provide a terminal connecting block. In practice, where it is desired to provide a large number of connections, such as between telephone subscribers in an apartment or office building and a central exchange, it is preferred to provide a plurality of helical connectors in a base member. For convenience, the plurality of connectors are generally arranged in parallel rows.

A large number of connections may be made on each helical connector. Several conductors may be inserted between each set of opposing faces of the coils which extend above the base. Thus, in a terminal connecting block in which ten coils of each helical connector extend above the block, there will be nine sets of opposing faces of the coils. Since three or more conductors may be inserted between each set of opposing faces, it can be seen that 3 twenty-seven or more connections may be made on each connector. Since a plurality of helical connectors are present in each terminal connecting block, the number of connections which may be made by means of one block is greatly increased over connecting blocks previously known to the art.

In FIGURE 1, a threaded stud 34 is secured, as by soldering, to the bottom of the connector 20., A nut 35 is thrcadably mounted on the stud 34. This type of electrical connector is particularly well suited for use with a peg board in the electronics field. The stud 34 may be inserted through a hole in the peg board and the nut 35 threaded onto the stud on the opposite side of the board thereby securing the connector to the peg board. As can be readily appreciated, the connector may thus be easily and quickly moved from one position to another as desired.

FIGURE 2 illustrates an electrical connector in combination with an insulated electrical conductor. The strip comprising each of the individual coils 21 of the helical connector 20 has a cross-sectional configuration 23 which comprises a partially planar surface 23b on both the top and bottom sides of the coil. The planar surface 23b on one side of the coil is interrupted by a projecting peak 230, the apex of the peak 23c defining an abrupt edge 23d. The planar surface on the other side of the coil is interrupted by a curved indentation 23a. The helical connector is constructed so that the peak 23c on one coil registers with the curved indentation 230 on the adjacent coil. When an insulated electrical conductor 27 is forced between two opposing coils, the electrical insulation 28 is pierced at the point of contact with the peak 23c, thereby establishing electrical contact between the conductor wire 29 and the connector 20. As is apparent from FIGURE 2, the insulated electrical conductor is crimped between the peak 23c and the indentation 23a. This has the efiect of securely holding the conductor wire. The opposing planar surface portions of the coils which are in contact with the insulated electrical conductor distribute any force which may be exerted on the top of the spring over a wide area, thereby avoiding any possibility of the conductor being severed at the point of contact With the peak 230 through pressure exerted on the top of the spring. By the use of this novel electrical connector, a more eifective electrical contact is made than is possible to obtain by conventional connectors such as those wherein a conductor is secured to a terminal post by means of a nut or where contact is provided between two curved surfaces. Moreover the tension due to the elasticity of the helical conductor in combination with the abrupt edges of the coil which are in contact with the conductor insures that the contact is positive and will not weaken due to metal fatigue after long periods of use, even under continuous vibration. The peak 234 is very eifective in removing the insulation from the conductor when the latter is forced into a position between the adjacent closely spaced coils.

Many variations and related embodiments other than those described above will be apparent to those skilled in the art. For example, a terminal connecting block may have the helical connectors extending all the way through the block so that connections may be made on either side. Moreover, the helical connectors constructed according to this invention may be used in structures other than the terminal blocks previously described-cg, they may be used in connecting one or more insulated conductors to a bolt, binding post or other electrical outlet.

This application is a continuation-in-part of my abandoned application Serial No. 72,670, filed November 30, 1960, for Novel Articles.

I claim:

A helical electrical connector comprising a continuous spiral of a strip of resilient, electrical conducting material forming a plurality of compact convolutions, said strip having across-sectional configuration comprising a partially planar surface on both the top and bottom sides thereof, the planar surface on one side of said strip being interrupted by a projecting peak and the planar surface on the other side of said strip being interrupted by a curved indentation, said peak and curved indentation extending longitudinally of the strip material, the projecting peak on one convolution being in registration with the curved indentation on the adjacent convolution, whereby the insulation on an insulated wire conductor is pierced and contact is achieved at separate points on said wire conductor when an insulated wire conductor is inserted be tween two adjacent convolutions of said connector.

References Cited in the file of this patent UNITED STATES PATENTS 941,893 Steinberger Nov. 30, 1909 2,309,311 Grohsgal Ian. 26, 1943 2,783,447 Watts Feb. 26, 1957 2,951,109 Bolhnier et a1 Aug. 30, 1960 3,066,274 Ellis Nov. 27, 1962 FOREIGN PATENTS 635,943 Great Brita-in Apr. 19, 1950 

